Encapsulation for the connection end or the termination end of an electric strip heater cable, and a method for producing it

Abstract

An encapsulation for the connection end or the termination end of a strip heater cable includes a moulded part, in which the strip heater cable has a core, including a plurality of electric conductors, and over the core, an insulating outer sheath made from a thermoplastic fluoropolymer material. The moulded part includes the same fluoropolymer material as the insulating outer sheath. The moulded part holds-an end section of the core of the strip heater cable and is welded to the insulating outer sheath, such that the connection end or the termination end is sealed in a hermetically tight fashion.

What is claimed is:  
     
       1. An encapsulation for a connection end or a termination end of an electric strip heater cable wherein the electric strip heater cable comprises a core having a plurality of electric conductors, and over the core, an insulating outer sheath made from a thermoplastic fluoropolymer material, comprising: 
       a moulded part for holding an end section of the core, wherein the moulded part is made from the thermoplastic fluoropolymer material, and welded to the insulating outer sheath to surround the connection end or the termination end in a hermetically tight fashion.  
     
     
       2. The encapsulation according to  claim 1 , wherein the moulded part farther comprises 
       a first section with a cylindrical lateral surface;  
       a second section bordering an end of the first section on the strip heater side and constructed in the shape of a half shell,  
       wherein an end section of the strip heater core is inserted into the second section, and the strip heater outer sheath is guided away over the second section and is welded beyond the second section to the cylindrical lateral surface of the first section.  
     
     
       3. The encapsulation according to  claim 2 , wherein at the connection end of the strip heater cable free ends of the conductors of the strip heater cable are individually connected to stripped ends of insulated pigtail leads, the pigtail leads being guided through at least one opening in the first section of the moulded part. 
     
     
       4. The encapsulation according to  claim 3 , wherein the free ends of the conductors of the strip heater cable are connected via crimp connectors to the stripped ends of the pigtail leads and in that the crimp connectors are arranged in the second section, in the shape of a half shell, of the moulded part. 
     
     
       5. The encapsulation according to either of claims  3  and  4 , wherein the moulded part further comprises a third section bordering another end of the first section, wherein in the third section, the moulded part has a plurality of tubular glands, integrally formed on the first section, for guiding through the pigtail leads. 
     
     
       6. The encapsulation according to  claim 5 , wherein the pigtail leads further comprises an insulation include the thermoplastic fluoropolymer material, and wherein the insulation of the pigtail leads in the third section is tightly welded to the inner surface of the glands. 
     
     
       7. The encapsulation according to one of claims  1 - 4 , wherein the end section of the strip heater core in the moulded part is sealed with the aid of a sealing means, in particular a polyurethane gel or a heat-resistant epoxy resin or cyanacrylate adhesive. 
     
     
       8. The encapsulation according to one of claims  1 - 4 , wherein the core of the strip heater cable has two parallel conductors, provided for conducting current and embedded parallel next to one another in a resistance material, an insulation surrounding these conductors, and a conducting shield around said insulation. 
     
     
       9. The encapsulation according to  claim 1  or  2 , wherein at the termination end of the strip heater cable, the end section of the strip heater core in the moulded part is plugged from its second section into a blind bore in its first section. 
     
     
       10. The encapsulation according to one of  claims 1  to  4 , wherein the moulded part is constructed as an elongate part with approximately the same cross section as the strip heater cable. 
     
     
       11. A method for producing an encapsulation according to one of claims  1 - 4 , wherein together with the core of the strip heater cable the moulded part traverses an extruder during application of the strip heater outer sheath. 
     
     
       12. The method for producing an encapsulation according to  claim 11 , wherein the outer sheath of the strip heater cable is welded to the moulded part by means of a heatable double-jaw tool, the welding preferably being performed in two stages in such a way that in the first stage the fluoropolymer material of the moulded part and of the outer sheath is only partly fused, fusing together occurring only in the second stage under the influence of pressure. 
     
     
       13. The method for producing an encapsulation according to  claim 12 , wherein the insulation of pigtail leads is welded to an inner surface of the glands in a separate welding operation.